ChangeIdUtil: Don't throw IOException

This could have only happened during the getBytes call. Instead, use
Constants.encode, which is a non-throwing implementation.

This change is binary compatible with existing code compiled against
older versions of JGit, although it might break compilation of
previously compiling code due to dead catch blocks.

Change-Id: I191fec5cac718657407230de141440e86d0151fb

org.eclipse.jgit/src/org/eclipse/jgit/util/ChangeIdUtil.java

@@ -42,7 +42,6 @@
  */
 package org.eclipse.jgit.util;
 
-import java.io.IOException;
 import java.util.regex.Pattern;
 
 import org.eclipse.jgit.lib.Constants;
@@ -90,12 +89,10 @@ public class ChangeIdUtil {
 	 *            The commit message
 	 * @return the change id SHA1 string (without the 'I') or null if the
 	 *         message is not complete enough
-	 * @throws IOException
 	 */
 	public static ObjectId computeChangeId(final ObjectId treeId,
 			final ObjectId firstParentId, final PersonIdent author,
-			final PersonIdent committer, final String message)
+			final PersonIdent committer, final String message) {
-			throws IOException {
 		String cleanMessage = clean(message);
 		if (cleanMessage.length() == 0)
 			return null;
@@ -116,8 +113,7 @@ public class ChangeIdUtil {
 		b.append("\n\n"); //$NON-NLS-1$
 		b.append(cleanMessage);
 		try (ObjectInserter f = new ObjectInserter.Formatter()) {
-			return f.idFor(Constants.OBJ_COMMIT, //
+			return f.idFor(Constants.OBJ_COMMIT, Constants.encode(b.toString()));
-					b.toString().getBytes(Constants.CHARACTER_ENCODING));
 		}
 	}